Rear vehicle-body structure of vehicle

ABSTRACT

A rear vehicle-body structure for increasing support rigidity for a rear suspension and consequently increase steering stability. The rear vehicle-body structure includes a first frame extending to connect a rear end lower portion of a combined body composed of a side sill and a pillar and a lower arm front support portion of a rear side housing, and having therein a closed cross-sectional space; a second frame extending to connect a rear end lower portion of a floor tunnel located at a vehicle-width-direction center portion of a vehicle-body bottom portion and bulging toward a vehicle upper side in a vehicle front-rear direction and the lower arm front support portion and having therein a closed cross-sectional space; and a third frame extending to connect a rear end upper portion of the floor tunnel and the lower arm front support portion, and having therein a closed cross-sectional space.

BACKGROUND Technical Field

The present disclosure relates to a rear vehicle-body structure of avehicle, including, for example, a suspension support portion supportinga rear suspension, a side sill extending in a vehicle front-reardirection on a vehicle front side relative to the suspension supportportion and on each side of a vehicle-body bottom portion, and a floortunnel bulging toward a vehicle upper side from avehicle-width-direction center portion of the vehicle-body bottomportion and extending in the vehicle front-rear direction.

Background Art

Vehicles such as sports cars require increased support rigidity for arear suspension to increase vehicle steering stability. A structure withincreased support rigidity for a rear suspension has been proposed,which is exemplified in Japanese Patent Laid-Open No. 2013-163470, asone of rear vehicle-body structures of a vehicle including a suspensionsupport portion, a side sill, and a floor tunnel as described above.

The rear vehicle-body structure disclosed in Japanese Patent Laid-OpenNo. 2013-163470 includes a rear suspension tower (suspension tower) as asuspension support portion, and also includes a rear reinforcement frame(30) extending from an upper rear end of a floor tunnel toward a vehiclerear side such that the frame is curved toward a vehicle-width-directionouter side as it goes toward the rear side and having its rear endconnected to a damper top of the suspension tower. This structure givesincreased support rigidity for the damper top of the rear suspension.

Generally, however, during traveling of the vehicle, large load isparticularly input to a lower arm support portion, among portions of arear suspension support portion, as the lower arm support portionsupports a lower arm that is directly connected to a rear wheel.

In this regard, Japanese Patent Laid-Open No. 2013-163470 does notdisclose providing the structure disclosed therein with a reinforcementframe and the like to connect the rear end of the floor tunnel and asupport portion (lower arm support portion) supporting a lower arm ofthe rear suspension. Japanese Patent Laid-Open No. 2013-163470 thusleaves room for improving support rigidity for the lower arm.

Hence, the present inventors have focused on the fact that large load isparticularly input to the lower arm support portion among portions ofthe rear suspension support portion during traveling of the vehicle, asdescribed above, and conceived of making a truss structure by connectingthe three points of the lower arm support portion, a rear end of theside sill, and a rear end lower portion of the floor tunnel with framemembers and the like.

Although this truss structure ensures support rigidity in the vehiclefront-rear direction and the vehicle width direction, increasing supportrigidity in the vehicle up-down direction is left for furtherconsideration.

SUMMARY

Accordingly, the present disclosure provides a rear vehicle-bodystructure of a vehicle that can increase support rigidity for a rearsuspension and consequently increase steering stability.

The present disclosure provides a rear vehicle-body structure of avehicle. The rear vehicle-body structure includes a rear side housingprovided with a lower arm support portion for supporting a lower arm ofa rear suspension; a side sill extending in a vehicle front-reardirection on each side of a vehicle-body bottom portion disposed on avehicle front side relative to the rear side housing; a pillar extendingin a vehicle up-down direction and having a lower portion thereof joinedto the side sill; a floor tunnel located at a vehicle-width-directioncenter portion of the vehicle-body bottom portion and bulging from thevehicle-body bottom portion toward a vehicle upper side and extending inthe vehicle front-rear direction; and a first frame extending so as toconnect the lower arm support portion and a rear end lower portion of acombined body composed of the side sill and the pillar. The first framehas therein a closed cross-sectional space in an extending direction ofthe first frame. The rear vehicle-body structure also includes a secondframe extending so as to connect a rear end lower portion of the floortunnel and the lower arm support portion. The second frame has a closedcross-section portion in an extending direction of the second frame. Therear vehicle-body structure further includes a third frame extending soas to connect a rear end upper portion of the floor tunnel and the lowerarm support portion. The third frame has a closed cross-section portionin an extending direction of the third frame.

With the above configuration, load in the vehicle front-rear directionand in the vehicle width direction that is included in the load input tothe rear side housing via the lower arm support portion during travelingof the vehicle can be received by a virtual truss structure having thefirst frame and the second frame, and also load in the vehicle up-downdirection that is included in the above load input to the rear sidehousing can be received by a virtual truss structure having the secondframe and the third frame.

Thus, the above configuration can increase support rigidity for thelower arm support portion, to which a larger load is input than to anupper arm support portion during traveling of the vehicle.

In one aspect of the present disclosure, a floor tunnel rear end sideedge portion is provided on each side in a vehicle width direction of arear end of the floor tunnel, wherein the floor tunnel rear end sideedge portion extends in the vehicle up-down direction so as to connectthe rear end upper portion and the rear end lower portion of the floortunnel, and the floor tunnel rear end side edge portion, the secondframe, and the third frame constitute a truss structure.

In one aspect of the present disclosure, the above configuration canfurther increase support rigidity particularly against load in thevehicle up-down direction that is included in the load input to the rearside housing via the lower arm support portion during traveling of thevehicle.

In one aspect of the present disclosure, a cross member is provided thatextends in the vehicle width direction so as to connect the rear endlower portion of the floor tunnel and the rear end lower portion of thecombined body and has therein a closed cross-sectional space in thevehicle width direction, wherein the cross member, the first frame, andthe second frame constitute a truss structure.

The above configuration can further increase support rigidityparticularly against load in the vehicle front-rear direction and in thevehicle width direction that is included in the load input from thelower arm to the rear side housing via the lower arm support portionduring traveling of the vehicle.

In one aspect of the present disclosure, a pair of left and right thirdframes are provided in a left-right integrated frame member, and theleft-right integrated frame member is formed of a single member.

The above configuration allows the left-right integrated frame member tobe formed without providing a joining portion for joining the pair ofleft and right third frames, and this allows the load input from thelower arm to the lower arm support portion during traveling of thevehicle to be effectively transmitted toward the vehicle front side viathe left-right integrated frame member.

In one aspect of the present disclosure, a backbone frame is disposed ona top face of the floor tunnel, the backbone frame extending in thevehicle front-rear direction along the top face, and a front end of theleft-right integrated frame member is connected to a rear end of thebackbone frame.

The above configuration allows the load input from the lower arm of therear suspension to the lower arm support portion during traveling of thevehicle to be transmitted to the backbone frame from the left-rightintegrated frame member.

In one aspect of the present disclosure, the left-right integrated framemember includes a connecting portion connecting front ends of the pairof left and right third frames in the vehicle width direction. Theconnecting portion is formed in a curved shape with a center portionthereof in the vehicle width direction being curved toward the vehiclefront side in vehicle plan view. The connecting portion of theleft-right integrated frame member is supported by a rear end of thefloor tunnel via a bracket, and the bracket includes a receiving portionfor receiving the connecting portion, and the receiving portion isformed in a curved shape conforming to the curved shape of theconnecting portion.

With the above configuration, the connecting portion is formed in thecurved shape and the receiving surface is formed in a curved shapeconforming to that curved shape, and this allows the receiving surfaceto firmly receive the connecting portion while being in contacttherewith along the curved shape.

The present disclosure not only improves side collision performance butalso improves front-end collision load transfer performance of a tunnelportion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of major parts of a vehicle having a rearvehicle-body structure of the present embodiment as viewed from a rearupper side;

FIG. 2 depicts a view as viewed in the direction of an arrow A in FIG.1;

FIG. 3 is a plan view of a rear side of the vehicle as viewed from anupper side in FIG. 1;

FIG. 4 is a back view of major parts of the vehicle having the rearvehicle-body structure of the present embodiment;

FIG. 5 is an enlarged view of a region X in FIG. 1; and

FIG. 6 is a right side view of major parts of the vehicle having therear vehicle-body structure of the present embodiment.

DETAILED DESCRIPTION

An embodiment of the present disclosure will be described with referenceto the drawings.

A vehicle in the present embodiment is a sports car that has a so-calledspace frame structure in which multiple extruded aluminum alloy framesare connected to form vehicle-body frames and also has a centerpillar-less structure with two side doors. A rear vehicle-body structureof such a vehicle will be described using FIGS. 1 to 6. As the rearvehicle-body structure of the vehicle of the present embodiment issymmetrical in shape, the below description will focus on a structure inthe right side of the vehicle. In FIG. 6, illustration of a floor tunnel81 and a backbone frame 85 has been omitted.

Also, for the sake of clear illustration, rear suspensions, rear wheelsand the like have been omitted in the figures and, in FIGS. 1 and 6,detailed illustration of lower arm support portions 21 a, 21 b (lowerarm front support portion 21 a and lower arm rear support portion 21 b),an upper arm support portion 22, and a damper support portion 23 hasbeen omitted.

In the figures, an arrow F represents a vehicle frontward direction, anarrow R represents a vehicle rightward direction, an arrow L representsa vehicle leftward direction, and an arrow U represents a vehicle upwarddirection.

As shown in FIG. 1, the vehicle having the rear vehicle-body structureof the present embodiment includes, on each of its left and right sides,double wishbone rear suspensions corresponding to respective left andright rear wheels, and the rear suspension includes a rear suspensiondamper, an upper arm, and a lower arm, though not shown in the figures.

The vehicle having the rear vehicle-body structure of the presentembodiment is provided with a floor panel 80 forming a bottom face of avehicle cabin and also provided with a floor tunnel 81 as a tunnelportion located at substantially the center in a vehicle width directionand extending in a front-rear direction of the vehicle and bulgingupward, i.e., toward the vehicle cabin.

The floor tunnel 81 is integrally formed of left and right side walls 81a and a top deck portion 81 b on a top side so as to form a gate shapeand is mainly responsible for vehicle-body rigidity. A pair of tunnelmembers 82 are formed at a corner between a top face of the floor panel80 and the respective side wall 81 a of the floor tunnel 81.

The tunnel member 82 has a closed cross-sectional space extending in thevehicle front-rear direction between the respective side wall 81 a ofthe floor tunnel 81 and the top face of the floor panel 80. While in thepresent embodiment the tunnel member 82 is formed from a front end ofthe floor tunnel 81 up to an intermediate portion thereof in the vehiclefront-rear direction, this is not by way of limitation and the tunnelmember 82 may also be formed up to a rear end of the floor tunnel 81(not shown in the figures).

The top deck portion 81 b of the floor tunnel 81 extends linearly in avehicle up-down direction and, as shown in FIG. 2, is slanted such thatits height increases as it goes toward the vehicle front side. As shownin FIG. 4, the floor tunnel 81 is formed such that its cross-sectionperpendicular to the vehicle front-rear direction defined by the pair ofleft and right side walls 81 a and the top deck portion 81 b isgate-shaped as described above, and the rear end of the floor tunnel 81is opened toward the vehicle rear side (see FIG. 4). However, as shownin FIG. 2, a rear portion of the side wall 81 a is extended toward thevehicle rear side farther than a rear end of the top deck portion 81 b,and this extended portion extends toward a vehicle-width-direction outerside as it goes toward the vehicle rear side. Hence, the rear portionsof the pair of left and right side walls 81 a are formed such that theyare more apart from each other in the vehicle width direction as they gotoward the vehicle rear side.

As shown in FIGS. 3 and 4, each of the left and right side walls 81 a ofthe floor tunnel 81 is integrally formed at its rear end (83 a) with alateral flange portion 83 protruding toward the vehicle-width-directionouter side via a bent portion 83 a.

As shown in FIGS. 1 to 4, a backbone frame 85 is disposed on the topdeck portion 81 b of the floor tunnel 81.

The backbone frame 85 is an extruded member having therein a closedcross-sectional space extending in the vehicle front-rear direction. Asshown in FIGS. 1 to 3, the backbone frame 85 extends toward the vehiclerear side until its rear end almost reaches the rear end of the floortunnel 81 and, as shown in FIG. 1, extends toward the vehicle front sidewith a front portion 85 f of the floor tunnel 81 bifurcated in vehicleplan view such that the bifurcated front portions 85 f are more apartfrom each other in the vehicle width direction as they go toward thevehicle front side. These bifurcated front portions 85 f of the backboneframe 85 are respectively joined to vehicle-body rigidity members (notshown) that extend in the vehicle front-rear direction at the vehiclefront side of a dash lower panel (not shown).

As shown in FIGS. 1 to 5, a connecting bracket 90 is provided above therear end of the floor tunnel 81, namely at the rear end of the backboneframe 85. As shown in FIGS. 1 and 2, the connecting bracket 90 isdisposed on the top deck portion 81 b at the rear end of the floortunnel 81 in a slanted orientation such that the connecting bracket 90is higher at its front portion than its rear portion, similarly to thebackbone frame 85.

The connecting bracket 90 is integrally formed of a base portion 91joined to the rear end of the backbone frame 85 and avehicle-width-center upper joined portion 92 to which a connectingportion 47 of a left-right integrated frame member 40 (described later;see FIGS. 1 to 5) is joined.

The vehicle-width-center upper joined portion 92 is formed such that itswidth in the vehicle width direction gradually increases outward from arear end of the base portion 91 toward the vehicle rear side and, asshown in FIG. 4, formed at its rear end with an opening 92A openedrearward.

As shown in FIG. 3, the vehicle-width-center upper joined portion 92 isformed so as to be able to accommodate the connecting portion 47 of theleft-right integrated frame member 40 (described later) via the opening92A, and a rear face of a front wall 92 f of the vehicle-width-centerupper joined portion 92 is formed in a curved shape in vehicle plan viewto conform to a curved shape of the connecting portion 47.

As shown in FIG. 4, a rear end of the connecting bracket 90, namely therear end of the vehicle-width-center upper joined portion 92 includes apair of left and right rear end side edges (93 a) extending in thevehicle up-down direction and a rear end upper edge (94 a) connectingupper ends of the pair of left and right rear end side edges in thevehicle width direction; theses edges define the aforementioned opening92A.

The connecting bracket 90 is integrally formed with the lateral flangeportions 93 protruding toward the vehicle-width-direction outer siderespectively from the left and right rear end side edges (93 a) each viaa bent portion 93 a. The connecting bracket 90 is integrally formed withan upper flange portion 94 protruding toward the vehicle upper side fromthe rear end upper edge (94 a) via a bent portion 94 a.

The lateral flange portions 93 formed at the rear end side edges (93 a)of the connecting bracket 90 and the lateral flange portions 83 formedat the rear ends (83 a) of the side walls (81 a) of the floor tunnel 81are disposed in an upper and lower relationship so as to extend in thevehicle up-down direction on the left and right sides.

As shown in FIGS. 1 to 3 and 5, a side sill 3 extending in the vehiclefront-rear direction is joined and fixed to each of the left and rightsides of the aforementioned floor panel 80.

As shown in FIGS. 1, 3, and 6, the side sill 3 is an aluminum alloyextruded member formed by extrusion and is disposed in the vehiclefront-rear direction on each side of the floor panel 80.

As shown in FIG. 6, the side sill 3 is formed of closed cross-sectionportions 31, 32 disposed spaced apart from each other in an upper andlower relationship and a connecting wall 33 connecting these closedcross-section portions 31, 32 on upper and lower sides.

Both of the closed cross-section portions 31, 32 on upper and lowersides (each of the upper closed cross-section portion 31 and the lowerclosed cross-section portion 32) have therein a closed cross-sectionalspace extending along the entire length of the side sill 3 in thevehicle front-rear direction.

A hinge pillar 34 extending in the vehicle up-down direction is disposedin a standing manner at a front end of the side sill 3. As shown in FIG.6, the hinge pillar 34 is an aluminum alloy extruded member formed byextrusion so as to have therein a closed cross-section portion extendinglinearly in the vehicle up-down direction, and is disposed in a standingmanner on the lower closed cross-section portion 32 such that the hingepillar 34 projects from the upper closed cross-section portion 31 towardthe vehicle upper side in a slanted orientation that positions the hingepillar 34 closer to the vehicle front side as it goes toward the vehicleupper side. The hinge pillar 34 is integrally joined, by arc welding orthe like, to the upper closed cross-section portion 31, the connectingwall 33, and the lower closed cross-section portion 32 at its respectiveportions facing them.

A rear pillar 35 (C pillar) extending in the vehicle up-down directionis disposed in a standing manner at a rear end of the side sill 3. Therear pillar 35 is an aluminum alloy extruded member formed by extrusionso as to have therein a closed cross-sectional space extending linearlyin the vehicle up-down direction, and is disposed in a standing manneron the lower closed cross-section portion 32 such that the rear pillar35 projects from the upper closed cross-section portion 31 toward thevehicle upper side in a slanted orientation that positions the rearpillar 35 closer to the vehicle rear side as it goes toward the vehicleupper side. The rear pillar 35 is integrally joined, by arc welding orthe like, to the upper closed cross-section portion 31, the connectingwall 33, and the lower closed cross-section portion 32 at its respectiveportions facing them.

In the following description, the side sill 3 and the rear pillar 35integrally joined to each other may also be referred to as a combinedbody 30. In FIG. 6, reference numerals 36 a, 36 b denote rear pillarreinforcements that reinforce the rear pillar 35 itself and joinedportions of the rear pillar 35 and the side sill 3.

As shown in FIG. 1, floor cross members 87, 88 are disposed on the floorpanel 80 between the side sill 3 and the side wall 81 a of the floortunnel 81 such that floor cross members 87, 88 extend linearly in thevehicle width direction so as to connect the side sill 3 and the sidewall 81 a.

The floor cross members 87, 88 include an intermediate floor crossmember 87 disposed substantially at an intermediate position on thefloor panel 80 in the vehicle front-rear direction and a rear end floorcross member 88 disposed at a rear end position on the floor panel 80 inthe vehicle front-rear direction.

The intermediate floor cross member 87 has a hat-shaped profile whosecross-section perpendicular to the vehicle width direction opensdownward (see FIG. 2) and forms a closed cross-sectional space betweenthe intermediate floor cross member 87 and the top face of the floorpanel 80. The rear end floor cross member 88 is formed by extrusion andforms therein a closed cross-sectional space.

In this example, a vehicle-width-direction outer end of the rear endfloor cross member 88 is joined, from the vehicle-width-direction innerside and by arc welding, to a lower portion of the rear pillar 35 joinedto the rear end of the side sill 3, namely a joined portion of the rearpillar 35 at which the rear pillar 35 is joined to the rear end of thelower closed cross-section portion 32 (see FIG. 1). Meanwhile, avehicle-width-direction inner end of the rear end floor cross member 88is joined, from the vehicle-width-direction outer side and by arcwelding, to a rear lower portion of the corresponding left or right sidewall 81 a of the floor tunnel 81 (see FIG. 1).

As shown in FIGS. 1 and 2, the rear portion of the vehicle of thepresent embodiment includes, on each of the left and right sidesthereof, a rear side frame 1, a rear side housing 10, and connectingframes 4A, 4B.

The rear side frame 1 is an aluminum alloy extruded member formed byextrusion and formed in a cylindrical shape with a substantiallyrectangular closed cross-section linearly extended in the vehiclefront-rear direction. On each side of the vehicle-body rear portion, therear side frame 1 extends in the vehicle-front rear direction from thefront side of the rear side housing 10 so as to project toward thevehicle rear side farther than a rear end of the rear side housing 10and is disposed substantially parallel to the vehicle front-reardirection.

Each front end of a pair of left and right crash cans 8 that arecomposed of a cylindrical body and the like for absorbing impact of acollision is connected to a rear end of the rear side frame 1 via a setplate 6 and a mounting plate 7. Rear ends of the pair of left and rightcrash cans 8 are connected by a bumper reinforcement 9.

The rear side housing 10 is disposed to substantially overlap the rearsuspension (not shown) in vehicle side view so that the rear sidehousing 10 can support the rear suspension from thevehicle-width-direction inner side, and is manufactured by die-castingof aluminum alloy, for example. As shown in FIGS. 1 and 3, the rear sidehousing 10 is disposed spaced apart from the side sill 3 toward thevehicle rear side and toward the vehicle-width-direction inner side.

Specifically, as shown in FIGS. 1 to 5, the rear side housing 10includes an upper raised wall 12, a lower raised wall 13 at a positionspaced apart from the upper raised wall 12 toward thevehicle-width-direction inner side, and a step portion 14 extendingsubstantially horizontally in the vehicle width direction so as toconnect an upper end of the upper raised wall 12 and a lower end of thelower raised wall 13 in the vehicle width direction. As shown in FIGS. 1to 3, the rear side frame 1 is disposed at a corner portion 24 betweenthe upper raised wall 12 and the step portion 14 of the rear sidehousing 10.

As shown in FIG. 6, a lower arm front support portion 21 a and a lowerarm rear support portion 21 b for pivotably supporting a lower arm (notshown) that is A-shaped in plan view are provided at a lower portion ofthe rear side housing 10.

The lower arm front support portion 21 a pivotably supports avehicle-width-direction inner end of the lower arm on the vehicle frontside, and the lower arm rear support portion 21 b pivotably supports avehicle-width-direction inner end of the lower arm on the vehicle rearside. The lower arm front support portion 21 a and the lower arm rearsupport portion 21 b are provided spaced apart from each other in thevehicle front-rear direction at a lower portion of the lower raised wall13 of the rear side housing 10.

An upper arm support portion 22 for pivotably supporting avehicle-width-direction inner end of an upper arm (not shown) that isI-shaped in plan view is provided at a position that is in the middle ofthe rear side housing 10 in the vehicle up-down direction and in thevehicle front side thereof, namely in the front side of the lowerportion of the upper raised wall 12 of the rear side housing 10.

In an upper portion of the rear side housing 10, namely at anintermediate position in an upper portion of the upper raised wall 12 ofthe rear side housing 10 in the vehicle front-rear direction, there isprovided a damper support portion 23 for pivotably supporting an upperend of a rear suspension damper (not shown) that extends in the vehicleup-down direction in a slanted orientation such that the rear suspensiondamper is positioned closer to the vehicle-width-direction inner side asit goes toward the vehicle upper side.

A front portion of the rear side housing 10 is configured such that rearends of three vehicle width outer connecting frames 4A (described later)(see FIG. 6) may be joined to the front portion from avehicle-width-direction outer face side.

Specifically, as shown in FIG. 6, in the front portion of the rear sidehousing 10 and at the intermediate position thereof in the vehicleup-down direction, there is provided a first upper outer frame rear endjoined portion 27 to which a rear end of a first upper outer frame 41(described later) located at the uppermost position among the threevehicle width outer connecting frames 4A (described later) is joined.

In the front portion of the rear side housing 10 and at the intermediateposition thereof in the vehicle up-down direction, there is provided asecond upper outer frame rear end joined portion 28 to which a rear endof a second upper outer frame 42 (described later) located between othertwo vehicle width outer connecting frames 41, 43 in the vehicle up-downdirection among the three vehicle width outer connecting frames 4A(described later) is joined.

In the front lower portion of the rear side housing 10, there isprovided a lower outer frame rear end joined portion 29 to which a rearend of a lower outer frame 43 located at the lowermost position amongthe three vehicle width outer connecting frames 4A (described later) isjoined.

As described above, the first upper outer frame rear end joined portion27 and the second upper outer frame rear end joined portion 28 areprovided adjacent to each other in an upper and lower relationship nearthe front side of the upper arm support portion 22 of the rear sidehousing 10.

Meanwhile, directly below and near the lower arm front support portion21 a, the lower outer frame rear end joined portion 29 is providedsubstantially at the same height as the lower arm front support portion21 a and the lower arm rear support portion 21 b.

The upper raised wall 12, the lower raised wall 13, and the step portion14 of the aforementioned rear side housing 10 are integrally formed andmade of aluminum alloy as a single member. In other words, as describedabove, almost entirety of the rear side housing 10, including the lowerarm support portions 21 a, 21 b, the upper arm support portion 22, thedamper support portion 23, the first upper outer frame rear end joinedportion 27, the second upper outer frame rear end joined portion 28, andthe lower outer frame rear end joined portion 29, is integrally formedof a single member by die-casting of aluminum alloy.

Now a description will be given of the connecting frames 4A, 4B. Asshown in FIGS. 1 to 5, the connecting frames 4A, 4B include the vehiclewidth outer connecting frames 4A (41, 42, 43) located between a rear endof the combined body 30 and the rear side housing 10 and connectingthem, and vehicle width inner connecting frames 4B (44, 45) locatedbetween the rear end of the floor tunnel 81 and the rear side housing 10and connecting them.

As shown in FIG. 6, multiple vehicle width outer connecting frames 4Aare provided spaced apart from each other in the vehicle up-downdirection.

Specifically, on each of the left and right sides of the vehicle-bodyrear portion, the vehicle width outer connecting frames 4A include thethree frames of the first upper outer frame 41, the second upper outerframe 42, and the lower outer frame 43 disposed in this order from thevehicle upper side to the vehicle lower side.

The first upper outer frame 41 is disposed substantially horizontally ata position slightly higher than the upper arm support portion 22. Afront end of the first upper outer frame 41 is joined to the rear pillar35 from a rear face of the rear pillar 35 at a position thereof on thevehicle upper side relative to an upper end of the side sill 3. The rearend of the first upper outer frame 41 is joined to the aforementionedfirst upper outer frame rear end joined portion 27 of the rear sidehousing 10 from the vehicle-width-direction outer face side.

The second upper outer frame 42 extends in a slanted manner in vehicleside view such that it is positioned closer to the vehicle upper side asit goes toward the vehicle rear side. A front end of the second upperouter frame 42 is joined to the rear pillar 35 from the rear face of therear pillar 35 at a position thereof corresponding to the rear end ofthe upper closed cross-section portion 31 in the vehicle up-downdirection of the side sill 3. The rear end of the second upper outerframe 42 is joined to the aforementioned second upper outer frame rearend joined portion 28 of the rear side housing 10 from thevehicle-width-direction outer face side.

The lower outer frame 43 is disposed horizontally in side view at aposition on the rear pillar 35 corresponding to the lower closedcross-section portion 32 of the side sill 3 and below the lower armfront support portion 21 a. A front end of the lower outer frame 43 isjoined to a rear end of the lower closed cross-section portion 32 of theside sill 3. The rear end of the lower outer frame 43 is joined to theaforementioned lower outer frame rear end joined portion 29 of the rearside housing 10 from the vehicle-width-direction outer face side.

As shown in FIG. 3, the aforementioned three vehicle width outerconnecting frames 4A (41, 42, 43) linearly extend in a slanted mannersuch that they are positioned closer to the vehicle-width-directioninner side as they go toward the vehicle rear side, and are integrallyjoined to both of the combined body 30 and the rear side housing 10 byMIG welding for example.

Multiple vehicle width inner connecting frames 4B are provided spacedapart from each other in the vehicle up-down direction.

Specifically, on each of the left and right sides of the vehicle-bodyrear portion, the vehicle width inner connecting frames 4B include anupper inner frame 44 and a lower inner frame 45 respectively disposed onthe vehicle upper and lower sides.

As shown in FIGS. 1 to 5, rear ends of both of the upper inner frame 44and the lower inner frame 45 are joined to the rear side housing 10 viaa frame mounting bracket 46 from a vehicle-width-direction inner faceside at a position overlapping the lower arm front support portion 21 a(see FIG. 6) in vehicle side view.

A rear end of the upper inner frame 44 and a rear end of the lower innerframe 45 are respectively joined to an upper portion and a lower portionof the frame mounting bracket 46 at positions adjacent to each other.

A front end of the upper inner frame 44 and a front end of the lowerinner frame 45 are respectively joined to a rear end upper portion(portion corresponding to the connecting bracket 90) and a rear endlower portion of the floor tunnel 81.

Both of the aforementioned vehicle width inner connecting frames 4B (44,45) linearly extend in a slanted manner such that they are positionedcloser to the vehicle-width-direction outer side as they go toward thevehicle rear side. As shown in FIG. 2, out of the two vehicle widthinner connecting frames 4B, the lower inner frame 45 extendshorizontally in vehicle side view while the upper inner frame 44 extendsin a slanted manner such that it is positioned upward as it goes towardthe vehicle front side.

Conforming to this, the backbone frame 85 and the connecting bracket 90are disposed in a slanted manner such that they are positioned upward asthey go toward the vehicle front side as described above, which makestheir inclination angles as much closer as possible to those of the pairof left and right upper inner frames 44 in vehicle side view.

As shown in FIGS. 1, 3, and 5, a position where the front end of thelower inner frame 45 and the rear end lower portion of the floor tunnel81 are joined substantially coincides with a position where thevehicle-width-direction inner end of the rear end floor cross member 88and the rear end lower portion of the floor tunnel 81 are joined. Also,a position where the front end of the lower outer frame 43 and a rearend lower portion of the combined body 30 are joined substantiallycoincides with a position where the vehicle-width-direction outer end ofthe rear end floor cross member 88 and the rear end lower portion of thecombined body 30 are joined.

Further, as shown in FIGS. 1 to 5, the frame mounting bracket 46 and thelower outer frame rear end joined portion 29 are provided respectivelyon inner and outer sides of the rear side housing 10 in the vehiclewidth direction but at portions substantially overlapping each other invehicle side view.

Hence, as shown in FIG. 5, the rear end floor cross member 88, the lowerinner frame 45, and the lower outer frame 43 constitute a first trussstructure T1. The first truss structure T1 is provided in a planeperpendicular to the vehicle up-down direction and rearwardly adjacentto the floor panel 80.

Also, floor tunnel rear end side edge portions (83 a, 93 a) (i.e., arear end side edge (83 a) of the side wall 81 a of the floor tunnel 81and a rear end side edge (93 a) of the connecting bracket 90), the upperinner frame 44, and the lower inner frame 45 constitute a second trussstructure T2. The second truss structure T2 is provided in an uprightorientation like the first truss structure T1 being pivoted upwardaround the lower inner frame 45, and is provided in a planesubstantially perpendicular to the vehicle width direction.

Here, the floor tunnel rear end side edge portions (83 a, 93 a) extendin the vehicle up-down direction, including the corresponding left orright side wall rear end of the backbone frame 85. In other words, thelateral flange portion 83 of the floor tunnel 81 and the lateral flangeportion 93 of the connecting bracket 90 extend linearly in the vehicleup-down direction so as to connect front ends of the upper inner frame44 and the lower inner frame 45. Additionally, the lateral flangeportion 83 and the lateral flange portion 93 are integrally formed, attheir base ends, with the bent portions 83 a, 93 a (ridges),respectively, extending in the vehicle up-down direction.

Thus, the lateral flange portion 83 and the lateral flange portion 93connect the front ends of the upper inner frame 44 and the lower innerframe 45 while ensuring strength between these front ends.

As shown in FIGS. 1, 3, and 4, in this example, the aforementioned pairof left and right upper inner frames 44 are formed as part of theleft-right integrated frame member 40. Specifically, the left-rightintegrated frame member 40 is formed by extrusion of a single member,such as aluminum alloy, into a cylindrical shape over its entire length,and is integrally formed in a substantially U-shape as a whole bybending a center portion in the longitudinal direction of the singlemember in an arc shape (circular arc shape in this example) such thatthe center portion projects frontward. The left-right integrated framemember 40 is integrally formed of the pair of linearly extending leftand right upper inner frames 44 and an arc-shaped connecting portion 47connecting their front ends.

The left-right integrated frame member 40 is disposed rearward of thefloor tunnel 81 such that the connecting portion 47 projects frontward.In other words, the left-right integrated frame member 40 is disposedsuch that the connecting portion 47 is inserted into thevehicle-width-center upper joined portion 92 of the connecting bracket90 via the opening 92A.

At this time, the front wall 92 f of the vehicle-width-center upperjoined portion 92 of the connecting bracket 90 is formed in an arc shapeconforming to the arc-shaped connecting portion 47, as described above.Hence, the connecting portion 47 inserted into the vehicle-width-centerupper joined portion 92 of the connecting member has its front edgeabutting on the rear face of the front wall 92 f of thevehicle-width-center upper joined portion 92 of the connecting bracket90 in the vehicle width direction and is integrally joined by arcwelding along the abutting portion. This allows for connecting thevehicle-width-center upper joined portion 92 of the connecting bracket90 and the connecting portion 47 such that the vehicle-width-centerupper joined portion 92 receives, on its rear side, the connectingportion 47 over the almost entire length thereof in the vehicle widthdirection.

In this way, the left-right integrated frame member 40 can have its pairof left and right upper inner frames 44 joined to the rear end upperportions of the left and right side walls 81 a of the floor tunnel 81 byhaving its connecting portion 47 joined to the connecting bracket 90.

This allows load that is input to the rear side housing 10 from thelower arm of the rear suspension via the lower arm support portions 21a, 21 b during traveling of the vehicle to be transmitted to thebackbone frame 85 from the upper inner frame 44 via the connectingbracket 90.

As shown in FIG. 1, the rear vehicle-body structure of the vehicle ofthe present embodiment described above includes: the rear side housing10 provided with the lower arm support portions 21 a, 21 b (see FIG. 6)for supporting the lower arm (not shown) of the rear suspension; theside sill 3 extending in the vehicle front-rear direction on each sideof a vehicle-body bottom portion disposed on the vehicle front siderelative to the rear side housing 10; the rear pillar 35 (pillar)extending in the vehicle up-down direction and having its lower portionjoined to the side sill 3; and the floor tunnel 81 located at thevehicle-width-direction center portion of the vehicle-body bottomportion and bulging from the vehicle-body bottom portion toward thevehicle upper side and extending in the vehicle front-rear direction. Asshown in FIGS. 1, and 3 to 5, the rear vehicle-body structure includes:the lower outer frame 43 (the first frame) extending so as to connectthe rear end lower portion of the combined body 30, which is composed ofthe side sill 3 and the rear pillar 35, and the lower arm front supportportion 21 a of the rear side housing 10 and having therein a closedcross-sectional space in the longitudinal direction (extendingdirection); the lower inner frame 45 (the second frame) extending so asto connect the rear end lower portion of the floor tunnel 81 and thelower arm front support portion 21 a and having therein a closedcross-sectional space in the longitudinal direction; and the upper innerframe 44 (the third frame) extending so as to connect the rear end upperportion of the floor tunnel 81 and the lower arm front support portion21 a and having therein a closed cross-sectional space in thelongitudinal direction.

With the above configuration, load in the vehicle front-rear directionand in the vehicle width direction that is included in the load input tothe rear side housing 10 via the lower arm support portions 21 a, 21 bduring traveling of the vehicle can be received by the virtual trussstructure having the lower outer frame 43 and the lower inner frame 45,and also load in the vehicle up-down direction that is included in theabove load input to the rear side housing 10 can be received by thevirtual truss structure (T2) having the lower inner frame 45 and theupper inner frame 44 (see FIG. 5).

Thus, the above configuration can increase support rigidity for thelower arm support portions 21 a, 21 b, to which a larger load is inputthan to the upper arm support portion during traveling of the vehicle.

In one aspect of the present disclosure, as shown in FIG. 3, the floortunnel rear end side edge portions (83 a, 93 a) are provided on eachside in the vehicle width direction of the rear end of the floor tunnel81. The floor tunnel rear end side edge portions (83 a, 93 a) extend inthe vehicle up-down direction so as to connect the rear end upperportion and the rear end lower portion of the floor tunnel 81, and asshown in FIG. 5, the floor tunnel rear end side edge portions (83 a, 93a), the lower inner frame 45, and the upper inner frame 44 constitutethe second truss structure T2 (truss structure).

The above configuration can further increase support rigidityparticularly against load in the vehicle up-down direction that isincluded in the load input to the rear side housing 10 via the lower armsupport portions 21 a, 21 b during traveling of the vehicle.

More specifically, with the above configuration, the floor tunnel rearend side edge portions (83 a, 93 a) have an end shape in the vehicleup-down direction that protrudes toward the vehicle rear side. Inparticular, in this example, the lateral flange portions 83, 93protruding toward the vehicle-width-direction outer side via the bentportions 83 a, 93 a are provided at the rear end of the side wall 81 aof the floor tunnel 81.

Thus, the floor tunnel rear end side edge portions (83 a, 93 a) areformed with ridge portions in the vehicle up-down direction thatcorrespond to the bent portions 83 a, 93 a. Additionally, as shown inFIG. 3, the rear end of the floor tunnel 81, including the rear end ofthe connecting bracket 90, is formed in a gate shape (U-shape) invehicle front view. Specifically, the floor tunnel rear end side edgeportions (83 a, 93 a) are formed such that upper ends thereof areconnected by the rear end upper edge (94 a) of the connecting bracket 90in the vehicle width direction, and the bent portions 83 a, 93 a, 94 a(ridge portions) are formed over the entire rear end of the floor tunnel81.

Meanwhile, lower ends of the pair of left and right side wall rear endsare respectively integrally connected to vehicle-width-direction innerends of the left and right rear end floor cross members 88. This gives ahigher rigidity to the floor tunnel rear end side edge portions (83 a,93 a) as compared to their nearby parts.

In the present embodiment, the second truss structure T2 can beconstituted by the lower inner frame 45, the upper inner frame 44, andthe floor tunnel rear end side edge portions (83 a, 93 a) connecting therear ends of these frames 45, 45 in the vehicle up-down direction.

Therefore, as described above, the rear vehicle-body structure of thevehicle of the present embodiment can have a further increased supportrigidity particularly against load in the vehicle up-down directionincluded in the load that is input to the rear side housing 10 via thelower arm support portions 21 a, 21 b during traveling of the vehicle.

In one aspect of the present disclosure, as shown in FIGS. 1 and 3 to 5,the rear vehicle-body structure includes the rear end floor cross member88 (cross member) extending in the vehicle width direction so as toconnect the rear end lower portion of the floor tunnel 81 and the rearend lower portion of the combined body 30 and having therein a closedcross-sectional space in the vehicle width direction (extendingdirection), and as shown in FIG. 5, the rear end floor cross member 88,the lower outer frame 43, and the lower inner frame 45 constitute thefirst truss structure T1 (truss structure).

The above configuration can further increase support rigidityparticularly against load in the vehicle front-rear direction and in thevehicle width direction that is included in the load input from thelower arm to the rear side housing 10 via the lower arm support portions21 a, 21 b during traveling of the vehicle.

In the present embodiment, the aforementioned two truss structures T1,T2 have the lower inner frame 45 in common as part of their components.This can effectively increase the support rigidity for the lower armsupport portions 21 a, 21 b without adding weight to the vehicle body.

In one aspect of the present disclosure, as shown in FIGS. 1, 2, and 4,the pair of left and right upper inner frames 44 are provided in theleft-right integrated frame member 40, and the left-right integratedframe member 40 is formed of a single member.

With this configuration, the left-right integrated frame member 40 isformed of a single member, which allows the left-right integrated framemember 40 to be formed without providing a joining portion for joiningthe pair of left and right upper inner frames 44. Hence, this allows theload that is input from the lower arm to the lower arm support portions21 a, 21 b during traveling of the vehicle to be effectively transmittedtoward the vehicle front side via the left-right integrated frame member40.

On the top deck portion 81 b (top face) of the floor tunnel 81, thebackbone frame 85 extending in the vehicle front-rear direction alongthe top deck portion 81 b is disposed, and the front end of theleft-right integrated frame member 40 is connected to the rear end ofthe backbone frame 85.

The above configuration allows the load that is input from the lower armof the rear suspension to the lower arm support portions 21 a, 21 bduring traveling of the vehicle to be transmitted to the backbone frame85 from the left-right integrated frame member 40.

In one aspect of the present disclosure, the left-right integrated framemember 40 includes the connecting portion 47 connecting the front endsof the pair of left and right upper inner frames 44 in the vehicle widthdirection. The connecting portion 47 is formed in a curved shape withits center portion in the vehicle width direction being curved towardthe vehicle front side in vehicle plan view. The connecting portion 47of the left-right integrated frame member 40 is supported by the rearend of the floor tunnel 81 via the connecting bracket 90 (bracket). Theconnecting bracket 90 includes the front wall 92 f (receiving portion)for receiving the connecting portion 47, and the front wall 92 f isformed in a curved shape conforming to the curved shape of theconnecting portion 47.

With the above configuration, the connecting portion 47 is formed in thecurved shape and the front wall 92 f is formed in a curved shapeconforming to that curved shape, and this allows the rear face of thefront wall 92 f to firmly receive the connecting portion 47 while beingin contact therewith along the curved shape.

The present disclosure is not limited to the configuration of the aboveembodiment and may be implemented in various embodiments.

What is claimed is:
 1. A rear vehicle-body structure of a vehicle, therear vehicle-body structure comprising: a rear side housing providedwith a lower arm support portion for supporting a lower arm of a rearsuspension; a side sill extending in a vehicle front-rear direction oneach side of a vehicle-body bottom portion disposed on a vehicle frontside relative to the rear side housing; a pillar extending in a vehicleup-down direction and having a lower portion thereof joined to the sidesill; a floor tunnel located at a vehicle-width-direction center portionof the vehicle-body bottom portion and bulging from the vehicle-bodybottom portion toward a vehicle upper side and extending in the vehiclefront-rear direction; a first frame extending so as to connect the lowerarm support portion and a rear end lower portion of a combined bodycomposed of the side sill and the pillar, the first frame having thereina closed cross-sectional space in an extending direction of the firstframe; a second frame extending so as to connect a rear end lowerportion of the floor tunnel and the lower arm support portion, thesecond frame having a closed cross-section portion in an extendingdirection of the second frame; and a third frame extending so as toconnect a rear end upper portion of the floor tunnel and the lower armsupport portion, the third frame having a closed cross-section portionin an extending direction of the third frame.
 2. The rear vehicle-bodystructure of a vehicle according to claim 1, further comprising: a floortunnel rear end side edge portion on each side in a vehicle widthdirection of a rear end of the floor tunnel, wherein the floor tunnelrear end side edge portion extends in the vehicle up-down direction soas to connect the rear end upper portion and the rear end lower portionof the floor tunnel, and the floor tunnel rear end side edge portion,the second frame, and the third frame constitute a truss structure. 3.The rear vehicle-body structure of a vehicle according to claim 2,further comprising: a cross member extending in the vehicle widthdirection so as to connect the rear end lower portion of the floortunnel and the rear end lower portion of the combined body and havingtherein a closed cross-sectional space in the vehicle width direction,wherein the cross member, the first frame, and the second frameconstitute a truss structure.
 4. The rear vehicle-body structure of avehicle according to claim 3, wherein a pair of left and right thirdframes are provided in a left-right integrated frame member, and theleft-right integrated frame member is formed of a single member.
 5. Therear vehicle-body structure of a vehicle according to claim 4, wherein abackbone frame is disposed on a top face of the floor tunnel, thebackbone frame extending in the vehicle front-rear direction along thetop face, and a front end of the left-right integrated frame member isconnected to a rear end of the backbone frame.
 6. The rear vehicle-bodystructure of a vehicle according to claim 5, wherein the left-rightintegrated frame member includes a connecting portion connecting frontends of the pair of left and right third frames in the vehicle widthdirection, the connecting portion is formed in a curved shape with acenter portion thereof in the vehicle width direction being curvedtoward the vehicle front side in vehicle plan view, the connectingportion of the left-right integrated frame member is supported by a rearend of the floor tunnel via a bracket, and the bracket includes areceiving portion for receiving the connecting portion, and thereceiving portion is formed in a curved shape conforming to the curvedshape of the connecting portion.
 7. The rear vehicle-body structure of avehicle according to claim 1, further comprising: a cross memberextending in the vehicle width direction so as to connect the rear endlower portion of the floor tunnel and the rear end lower portion of thecombined body and having therein a closed cross-sectional space in thevehicle width direction, wherein the cross member, the first frame, andthe second frame constitute a truss structure.
 8. The rear vehicle-bodystructure of a vehicle according to claim 1, wherein a pair of left andright third frames are provided in a left-right integrated frame member,and the left-right integrated frame member is formed of a single member.9. The rear vehicle-body structure of a vehicle according to claim 2,wherein a pair of left and right third frames are provided in aleft-right integrated frame member, and the left-right integrated framemember is formed of a single member.
 10. The rear vehicle-body structureof a vehicle according to claim 4, wherein the left-right integratedframe member includes a connecting portion connecting front ends of thepair of left and right third frames in the vehicle width direction, theconnecting portion is formed in a curved shape with a center portionthereof in the vehicle width direction being curved toward the vehiclefront side in vehicle plan view, the connecting portion of theleft-right integrated frame member is supported by a rear end of thefloor tunnel via a bracket, and the bracket includes a receiving portionfor receiving the connecting portion, and the receiving portion isformed in a curved shape conforming to the curved shape of theconnecting portion.
 11. The rear vehicle-body structure of a vehicleaccording to claim 7, wherein a pair of left and right third frames areprovided in a left-right integrated frame member, and the left-rightintegrated frame member is formed of a single member.
 12. The rearvehicle-body structure of a vehicle according to claim 8, wherein abackbone frame is disposed on a top face of the floor tunnel, thebackbone frame extending in the vehicle front-rear direction along thetop face, and a front end of the left-right integrated frame member isconnected to a rear end of the backbone frame.
 13. The rear vehicle-bodystructure of a vehicle according to claim 8, wherein the left-rightintegrated frame member includes a connecting portion connecting frontends of the pair of left and right third frames in the vehicle widthdirection, the connecting portion is formed in a curved shape with acenter portion thereof in the vehicle width direction being curvedtoward the vehicle front side in vehicle plan view, the connectingportion of the left-right integrated frame member is supported by a rearend of the floor tunnel via a bracket, and the bracket includes areceiving portion for receiving the connecting portion, and thereceiving portion is formed in a curved shape conforming to the curvedshape of the connecting portion.
 14. The rear vehicle-body structure ofa vehicle according to claim 9, wherein a backbone frame is disposed ona top face of the floor tunnel, the backbone frame extending in thevehicle front-rear direction along the top face, and a front end of theleft-right integrated frame member is connected to a rear end of thebackbone frame.
 15. The rear vehicle-body structure of a vehicleaccording to claim 9, wherein the left-right integrated frame memberincludes a connecting portion connecting front ends of the pair of leftand right third frames in the vehicle width direction, the connectingportion is formed in a curved shape with a center portion thereof in thevehicle width direction being curved toward the vehicle front side invehicle plan view, the connecting portion of the left-right integratedframe member is supported by a rear end of the floor tunnel via abracket, and the bracket includes a receiving portion for receiving theconnecting portion, and the receiving portion is formed in a curvedshape conforming to the curved shape of the connecting portion.
 16. Therear vehicle-body structure of a vehicle according to claim 11, whereina backbone frame is disposed on a top face of the floor tunnel, thebackbone frame extending in the vehicle front-rear direction along thetop face, and a front end of the left-right integrated frame member isconnected to a rear end of the backbone frame.
 17. The rear vehicle-bodystructure of a vehicle according to claim 11, wherein the left-rightintegrated frame member includes a connecting portion connecting frontends of the pair of left and right third frames in the vehicle widthdirection, the connecting portion is formed in a curved shape with acenter portion thereof in the vehicle width direction being curvedtoward the vehicle front side in vehicle plan view, the connectingportion of the left-right integrated frame member is supported by a rearend of the floor tunnel via a bracket, and the bracket includes areceiving portion for receiving the connecting portion, and thereceiving portion is formed in a curved shape conforming to the curvedshape of the connecting portion.
 18. The rear vehicle-body structure ofa vehicle according to claim 12, wherein the left-right integrated framemember includes a connecting portion connecting front ends of the pairof left and right third frames in the vehicle width direction, theconnecting portion is formed in a curved shape with a center portionthereof in the vehicle width direction being curved toward the vehiclefront side in vehicle plan view, the connecting portion of theleft-right integrated frame member is supported by a rear end of thefloor tunnel via a bracket, and the bracket includes a receiving portionfor receiving the connecting portion, and the receiving portion isformed in a curved shape conforming to the curved shape of theconnecting portion.
 19. The rear vehicle-body structure of a vehicleaccording to claim 14, wherein the left-right integrated frame memberincludes a connecting portion connecting front ends of the pair of leftand right third frames in the vehicle width direction, the connectingportion is formed in a curved shape with a center portion thereof in thevehicle width direction being curved toward the vehicle front side invehicle plan view, the connecting portion of the left-right integratedframe member is supported by a rear end of the floor tunnel via abracket, and the bracket includes a receiving portion for receiving theconnecting portion, and the receiving portion is formed in a curvedshape conforming to the curved shape of the connecting portion.
 20. Therear vehicle-body structure of a vehicle according to claim 16, whereinthe left-right integrated frame member includes a connecting portionconnecting front ends of the pair of left and right third frames in thevehicle width direction, the connecting portion is formed in a curvedshape with a center portion thereof in the vehicle width direction beingcurved toward the vehicle front side in vehicle plan view, theconnecting portion of the left-right integrated frame member issupported by a rear end of the floor tunnel via a bracket, and thebracket includes a receiving portion for receiving the connectingportion, and the receiving portion is formed in a curved shapeconforming to the curved shape of the connecting portion.